The object of the present invention is an improved laboratory device and a method for subjecting the same rock sample to successive treatments, without any intermediary handling. The device according to the present invention particularly improves the laboratory techniques for isolating the organic matter fraction which is contained in the rocks and which cannot be extracted by solubilization.
These isolation techniques generally comprise the use of mineral acids for solubilizing the constituent minerals of the rock, after grinding the rock. Hydrochloric acid is first utilized for solubilizing the carbonates, then hydrofluoric acid is used for solubilizing the silicates. Additional treatments are sometimes carried out to solubilize some of the minerals standing up to the previous treatments. It can for example be attempted to solubilize the pyrite, or a fraction of it, by means of hydrogenating or oxidizing reagents.
At the end of these treatments, the insoluble organic matter is recovered by centrifuging or by filtering. Centrifugings or filterings are also necessary between these different treatments. The total treatment time is very long and may reach several hundred hours, notably if one wishes to isolate from certain rocks an organic matter no longer containing more than an amount of mineral impurities sufficiently low for the subsequent analyses to be carried out in good conditions. Besides, the quality of the preparations is often poorly reproducible, the handlings are numerous and are performed in non-satisfactory security conditions.
Prior art can be illustrated by French Patent 2,290,666.
The devices according to prior art utilize mechanical stirring means for stirring the mixture of reagent and rock.
These means have serious drawbacks. On one hand, the stirring element, which is often a helix, wears out and is affected by the aggressive products that are used for treating the rock sample. The products of this parasitic attack may distort the measurements. On the other hand, such a stirring device requires the use of a shaft, a helix, an electric engine, pulleys, belts and/or speed reducers. The use of such parts makes the equipment bulky and uneasy to handle.
Besides, these parts are easily damaged by heat while the treating of the rock sample generally requires at least one operation involving an increase in temperature.